This invention is concerned with a centrifuge having a drum driven by a main drive motor and having a worm gear located inside the drum. More particularly, the invention relates to such a centrifuge in which the worm gear is driven by a differential drive unit which contains a hydraulic motor and has a different rate of rotation from that of the drum.
Because of its advantageous adjustability, a hydraulic drive unit continues to prove its worth as a differential drive unit for the rotary motion between the drum and the worm gear of a decanter centrifuge. When used for this purpose, a hydraulic drive unit can in a familiar manner, be a slip drive unit in which a hydraulic motor which is acted upon by the pressure medium through rotation ducts rotates with the drum, or it can be differential drive unit in which a stationary hydraulic motor takes care of the differential rotary motion between the drum and the worm gear through a planetary differential gearing.
In these two known hydraulic systems, the fact that a relatively large pump must be installed to deliver the flow of the pressure medium which is required in borderline cases and that the hydraulic system cannot be used to bring the drum to speed or to control the rate of rotation of the drum are distinct disadvantageous shortcomings.